1. Field of the Invention
This invention relates in general to communication systems, and more particularly, to a method and system for managing information communicated over a Simple Integrated Media Access (SIMA) network or an interface between a SIMA and other networks, such as a conventional IP (Internet Protocol) or ATM network, by using priorities defined by a customer.
2. Description of Related Art
Simple Integrated Media Access (SIMA) is a new way of introducing new properties for packet-based data networks, such as TCP/IP or ATM networks. The basic idea of SIMA relies on the use of eight packet-discarding priority levels, as described in details in the above-mentioned patent applications, entitled xe2x80x9cNOMINAL BIT RATE. NETWORK SERVICExe2x80x9d, NC 7664, Ser. No. 08/821,273, filed Mar. 20, 1997 now U.S. Pat. No. 6,163,808; U.S. patent application entitled xe2x80x9cCELL SCHEDULING SYSTEM AND METHOD FOR NETWORK NODESxe2x80x9d, NC 7665, Ser. No. 08/822,266, filed March 20, 1997 now U.S. Pat. No. 6,081,505, and U.S. patent application entitled xe2x80x9cACCOUNTING SYSTEM AND METHOD FOR A NOMINAL BIT RATE NETWORK SERVICExe2x80x9d. NC 7701, Ser. No. 08/822,270, filed Mar. 20, 1997 now U.S. Pat No. 6,047,326, the subject matter of which is hereby incorporated by reference. Every data packet is equipped with a priority level (PL) that can be an integer between 0 and 7.
In a basic SIMA network, priority is used for selecting packets that are discarded during congestion of a network node. The priority is determined from the ratio of a momentary actual bit rate of the source (a customer) to the Nominal Bit Rate (NBR) assigned to the source (the customer). This determination is generally performed in a network access node that is the first network element to receive a packet from a customer equipment.
One problem of the basic SIMA network is that it does not make possible for a customer to define what is the importance of a packet or cell, for example, in a case of 2-layer video coding, in which one layer video coding requires a higher priority level than the other layer. Another example is that a customer may want to send acknowledge packets with a higher priority than its normal data packets.
A possible solution to solving this problem is to use one connection for each desired priority level and to allocate proper Nominal Bit Rate (NBR) for two or more connections. However, the use of different connections has at least two drawbacks. One is that the network cannot usually guarantee that two or more connections use the same route for sending the packets. As a result, the delays of the two or more connections may differ significantly. This may yield problems at a receiving equipment. The second drawback is that the total NBR cannot be divided flexibly between the two or more connections, and on the other hand the NBR must be determined separately for the two or more connections. Accordingly, if a customer is only sending packets on a certain priority level, the NBR of the other priority level will be wasted.
Another problem of the basic SIMA concept is that a NBR measuring algorithm is only designed for fixed size packets or cells. It does not satisfy the need to measure NBR for variable size packets.
In the basic SIMA network, each connection (i) has a Nominal Bit Rate (NBR), which determines the relative amount of network capacity liable to the connection at a given instant. The network measures the actual bit rate (MBR) of the connection at the network interface. After the measurement, the network gives each packet (j) a priority, PL(i,j), based on the MBR to NBR ratio using the following formula:                               x          =                      4.5            -                          ln              ⁢                              xe2x80x83                            ⁢                                                (                                                            MBR                      ⁡                                              (                                                  i                          ,                          j                                                )                                                                                    NBR                      ⁡                                              (                        i                        )                                                                              )                                /                ln                            ⁢                              xe2x80x83                            ⁢                              (                2                )                                                    ⁢                  
                ⁢                              PL            ⁡                          (                              i                ,                j                            )                                =                      {                                                            6                                                                                            if                      ⁢                                              xe2x80x83                                            ⁢                      x                                        ≥                    6                                                                                                                    Int                    ⁡                                          (                      x                      )                                                                                                                                  if                      ⁢                                              xe2x80x83                                            ⁢                      0                                         less than                     x                     less than                     6                                                                                                0                                                                                            if                      ⁢                                              xe2x80x83                                            ⁢                      x                                        ≤                    0                                                                        }                                              (        1        )            
where Int(x) is the integer part of x.
One drawback of this method is that a customer can effect on the priority of an individual packet only by changing an interarrival time between consecutive packets, because the NBR of the connection cannot be changed in time scale of a packet. This method is difficult for most customer""s applications.
Accordingly, there is a need in communication industry for a network management architecture and method that allow a customer to define what is the importance of a data packet communicated over a Simple Integrated Media Access (SIMA) network. In addition, there is a need for a network management architecture and method that measure NBR based on variable size packets. The present invention provides a solution to the above and other problems and offers other advantages over the prior art.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and system for using priorities defined by the customer in a SIMA network.
The present invention relates to communication systems, and more particularly, to a method and system for managing information communicated over a Simple Integrated Media Access (SIMA) network or an interface between a SIMA and other networks, such as a conventional IP (Internet Protocol) or ATM network, by using priorities defined by a customer.
In one embodiment, the present invention provides a system which includes a priority level pool unit generating at least two priority levels for a Nominal Bit Rate (NBR) based on at least two relative priorities defined by a customer and a network access unit transmitting packets of information via a network with one of the at least two priority levels. Accordingly, the Nominal Bit Rate (NBR) is used dynamically between two (or several) traffic sub-streams (or routes) with different priorities.
Further in one embodiment, the system further includes a customer management unit, the customer management unit providing the NBR to the priority level pool unit, the NBR being predefined between the customer and the network.
Still in one embodiment, the network is a SIMA network. Alternatively, the network can be other networks such as a conventional IP (Internet Protocol) or ATM network, or a network between SIMA network and other networks. The networks of the present invention use a service with two priority levels.
Yet in one embodiment, the at least two priority levels of the packets are determined by using an MBR (actual bit rate) to NBR ratio added by the relative priorities defined by the customer. The actual bit rate of both priority levels is measured separately. The total measured bit rate (MBR) are calculated by weighed sum of the measured results. In one embodiment, the total MBR are calculated in a way such that the weight is doubled when the priority level is increased by one.
In one embodiment, the present invention also provides a method which includes generating at least two priority levels for a Nominal Bit Rate (NBR) based on at least two relative priorities defined by a customer and transmitting packets of information via a network with one of the at least two priority levels.
Further in one embodiment, the method further includes providing the NBR to a priority level pool unit by a customer management unit of the network, the NBR being predefined between the customer and the network; providing the at least two relative priorities, defined by the customer, to the priority level pool unit; generating at least two priority levels by the priority level pool unit for the packets of information at a network access unit; and transmitting the packets of information with one of the at least two priority levels via the network access unit.
Still in one embodiment, the network is a SIMA network. The present invention can also be used in the other networks, such as a conventional IP (Internet Protocol) or ATM network, which may require a service with two or more priority levels. In addition, if a NBR is attached to an interface between networks, rather than a network access node or connection of a network, the present invention can provide a service that the NBR is divided dynamically among different connections, which may have different quality requirements.
One advantage of the present invention is that it allows the customer to define the priority which corresponds to the importance of a packet. The route of all packets or cells is the same for both priority levels. Further, both priority levels use the same NBR.
Another advantage of the present invention is that the NBR measuring algorithm is designed to work with fixed size packets as well as variable size packets.
A further advantage of the present invention is that it improves interoperability between SIMA network and other networks or services. These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.